Vac bed draw down and stuff

[ZooCity]

How long should a larger vac bed, i.e. able to shoot (2) 23x31 or 25x36 at once, take to draw down and where is the vac gauge at typically? 

Where and how do you place the string on it?  We have a pc of romex sheathing that is taped to a little cup that's over where the vac hose come through the glass and it gets place over one corner of one frame.  It's how it was when we got the unit but I'm certainly not sure if it's right.

Our draw down has been super slow.  The gauge is at 15 and then goes up to about 18-20 when it gets drawn down all the way.  I know the blanket and gasket on ours needs replaced but was just wondering for comparison. 

[tonypep]

on our units 25 to 27. 12 seconds

[Sbrem]

our vac frame is huge, but if I were making one, I'd want at least 6" all around. the string goes from the vacuum hole to the inside of the frame. The idea is that air is pulled through the string (I hope it's a piece of rope actually) after the rubber starts to seal around the outside... We don't have a gauge, but when it's tight, it gets right into the corners of the frame, and all the way around it; very, very snug.

Steve

[ebscreen]

A small leak, typically around the edge somewhere, will result in extended vacuum times.
Basically it leaks and leaks until the vacuum/drawdown of the blanket overcomes it and then seals it.
Vacuum pump size will play a role as well.

[ZooCity]

Reckon it's a leak or three.  What you described sounds pretty accurate eb. 

Does spec'ing a bigger/badder pump get a faster draw down generally?  More volume of air being sucked perhaps?

[ebscreen]

Yep.

Our old huge frame had a 1/2hp vacuum I think. Volume of a Hoover and could suck the chrome
off a ball hitch. The motor eventually started tripping the over-temp for some reason, and I replaced it with a 1/4
hp I had. It sucked.